This is so cool! We can quickly learn to use a "third limb" in a virtual reality environment!

the white “third limb”

...we found that, when compared to performance in a “normal” avatar body (with the ability to step forward, and two avatar arms that were controlled by the participant’s two physical arms), participants could hit more targets using an avatar with three upper limbs, which allowed greater reach with less physical movement. This was true even though motions mapped from the participants’ tracked movements were rendered in a different modality (rotation of the wrist moved the avatar’s third limb in arcs corresponding to pitch and yaw). Use of more intuitive mappings might enable even faster adaptation and greater success. These initial experiments confirmed that people could rapidly learn to use a novel body and succeed in that body compared to a more “normal” configuration, even when the body schema differs radically from that of the user’s own body.